Heel releasing device for safety ski bindings



Dee.` 10, 1968 H. scHEla 3,415,530

HEEL RELEASING DEVICE FOR SAFETY SKI BINDINGS Filed July e, 196e INVENTOR 2 6 HERMANN scr-:EIB

BY mm,mf%v

ATTORNEYS United States Patent O 3,415,530 HEEL RELEASING DEVICE FOR SAFETY SKI BINDINGS Hermann Scheib, Garmisch-Partenkirchen, Germany, as-

signor to Hannes Marker, Garmisch-Partenkirchen, Germany Filed July 6, 1966, Ser. No. 563,145 Claims priority, application Germany, July 8, 1965, M 65,877 1 Claim. (Cl. 280-11.35)

ABSTRACT F THE DISCLOSURE A heel release device for safety ski bindings of the type which pivotally moves about an axis parallel to the surface of the ski which consists of a yoke and lever combination which is engaged with a ski by means of a pair of tensile elements having loops at one end to engage the yoke and attached at their other ends to the ski. A pusher member consisting of an angle member to engage a heel groove also includes a rod which slidably engages with the lever. A spring is effective between the rod and lever. The yoke and lever combination is provided with adjustable racks to preset the position of the yoke and lever combination relative to the uppers of the boot.

This application relates to a heel releasing device for safety ski bindings, which is pivotally movable about an axis parallelto the surface of the ski and which is held by two tensile elements, which extend forwardly on the sides of the skiing boot. This heel releasing device comprises a pusher member for engaging the heel groove of the skiing boot, a pivoted lever for operating the pusher member, which lever extends in position for use approximately at right angles to the surface of the ski, and aspring, which is effective between the pusher member and the tensile elements and is arranged so that in the operative position of the pivoted lever the pusher member engages the heel in the groove under pressure, the tensile elements being connected by a shaft and said shaft and the pusher member being relatively movable in such a manner that the extension of the line of contact between the pusher member and the heel in the groove extends below the tensile elements when the releasing device is in position for use whereas the line of Contact is raised above the tensile elements in response to an excessive tensile force acting on the heel.

The present invention relates to an improvement of such heel releasing device and resides in that the spring element consists of a gas spring, known per se, which preferably constitutes the pivoted lever, and the pusher member is mounted on the piston rod of said gas spring.

The gas spring is a closed cylinder, which contains a gas under pressure and in which a piston is slidable, which is provided at one end with a piston rod. As the chambers on both sides of the piston communicate through a bore in the piston, a displacement of the piston cannot cause an additional compression of the filling gas. As the piston rod is mounted only at one end of the piston, the piston has differential end faces so that a displacement of the piston will always be opposed by a force which is equal to the product of the internal pressure and the cross-sectional area of the piston rod. This arrangement results in a compression spring having an approximately constant spring rate because the internal pressure in the gas spring cylinder remains approximately constant, except for the small change in pressure which is caused by the change in volume due to the movement of the piston rod into the cylinder. This change may be kept very small.

3,415,530 Patented Dec. 10, 1968 The invention will be explained more in detail in the following description with reference to the drawing, in which:

FIG. 1 is a side elevation showing a heel releasing device in engaged position,

FIG. 2 is a rear elevation of the same embodiment,

FIG. 3 is a top plan view showing the embodiment of FIG. l, and

FIG. 4 is a sectional view showing the embodiment of FIG. l.

The tensile elements of the heel releasing device extending forwardly along the sides of the heel of the boot con` sist of wire cables 1, 2 and are connected to a turntable or to the side faces of the ski in known manner, either rigidly or for adjustment in the longitudinal direction of the ski. The wire cables 1, 2 have loop ends 3, 4, which are hooked onto mountings 5, 6 carried by a yoke 7, which is connected to the gas spring cylinder 8. The yoke 7 and the gas spring cylinder 8 form together the pivoted lever of the heel releasing device. It is no longer necessary to provide a special cylinder for receiving the spring because the gas spring comprises inherently a cylinder so that commercially available gas springs may be used in a particularly simple design of the heel. tightener.

The pusher member consists of an angle member 11, which is secured by a nut 10 to the piston rod 9 of the gas spring and has an extension 12, which conforms to the heel groove and engages the heel in said groove. The point of contact in the heel groove lies below the tensile elements 1, 2 in position for use, shown in FIG. l, so that the tensile elements 1, 2 hold the heel releasing device in this position. During a forward fall of the skier, the pusher member 11 is displaced upwardly by its extension 12 owing to the lifting of the heel of the boot so that the piston rod 9 of the gas spring is urged into the gas spring cylinder 8 owing to the connection of said piston rod to the pusher member. During this movement, the position of the tensile elements 1, 2 remains substantially unchanged. If the point of contact between the pusher member 11 and the heel of the boot in the groove is moved above the line of action of the tensile elements 1, 2 during this movement, the gas spring immediately effects a pivotal movement of the heel releasing device to its release position.

The mode of operation and structure of the gas spring will be explained with reference to FIG. 4. This gas spring enables particularly surprising effects to be achieved in connection with a heel releasing device. The gas spring consists of the cylinder 8, the piston 16 and the piston rod 9. The cylinder is sealed against the piston rod 9 by a sealing system 23, which serves also for guiding the piston rod 9, so that a closed cylinder space is defined, which contains a highly compressed gas. As is apparent from FIG. 4, the sealing bushing 23 is provided at its end face confronting the interior of the cylinder with an annular recess so that a sealing lip s formed, which is forced against the cylinder wall by the gas pressure which enters the annular recess. In this way the sealing effect is improved.

The cylinder space is divided by the piston 16 into two chambers 21, 22, which communicate with each other by connecting bores 17, 18 formed in the piston 16. The piston has end faces 19, 20 differing in area because the piston rod is provided only at one end face. The area of surface 19 exceeds the area of surface 20 by the cross-sectional area of t-he piston rod. For this reason, a displacement of the piston 16 into the gas spring is always opposed by a force which is equa-l to the product of gas pressure and cross-sectional area of the piston rod. This force acting in the direction of the arrows always tends to urge the piston 16 toward its one end position, in which it abuts :the sealing system 23. Said opposing force is approximately constant in any position because the connecting bores 17, 18 enable at any time an equalization of pressure between the c-hambers 21, 22, and an additional compression on one side is avoided. A slight increase in pressure within the gas spring results only from the fact that the pushing of the piston rod 9 into the gas spring results in Ia change in volume in the cylinder. This change in volume may be kept relatively small. As a result of the described mode of operation, the pressure by which the boot is forced by the pusher member 11 and its extension 12 onto the surface of the ski and yagainst the toe iron remains virtually constant so that there is no need to overcome an increasing spring force even during a release movement, as was previously always the case.

The gas spring which has been described hereinbefore is capable of producing another, additional effect. If the connecting bores 17, 18 are very small relative to the area of the piston 16, a full equalization of pressure will not be possible during a very quick, short-time piston movement because the gas cannot ow from one chamber into the other during the short time. This results in an additional compression in one chamber so that the opposing force is increased. An equalization of pressure is possible only during a piston movement taking place for a longer time. For this purpose, the diameter of the piston faces is preferably to 20 times the diameter of the connecting bores. The spring according to the invention may thus be utilized for an additional holding of the heel onto the surface of the ski because a relatively strong force will oppose a short-time lifting movement of the heel, as occurs during normal skiing. On the other hand, the reliability of the action of the releasing device in response to a forward fall will not be adversely affected because in such case the force acts during a somewhat longer time so that the release of the foot is ensured. This arrangement enables the use of relatively small steady-state spring forces so that injuries .are avoided with an increased safety.

In accordance with the invention, the heel releasing device bears on the uppers of the boot suitably by a cam 13, which conforms to the uppers of the boot and is adjustably mounted in the yoke 7 in a series of teeth 14 by means of a nut so that a uniform operative position of the heel releasing device can be ensured with boots of different shapes. This arrangement enables `also to a certain extent an adjustment of the point of contact between the pusher member 11, 12 and the heel in the groove relative to the line of action of the tensile elements 1, 2.

The heel releasing device -according to the invention is suitably closed at the top by a eap 24, which may consist of plastics material.

What is claimed is:

1. A heel release device for safety ski bindings of the type which pivotally moves about an axis parallel to the surface of the ski upon which the device is to be mounted comprising pusher means for engaging the heel groove of a ski boot, lever means slidingly engaged with the pusher Imeans, which lever means extends in position for use approximately at right angles to t-he surface of the ski, spring means effective between the pusher means and the lever means, and two tensile elements, one of their ends connected to opposite sides of said lever means and the other of their ends to be anchored to the ski, said releasing device being constructed and arranged so that in the position for use of the lever means the pusher means engages the heel groove under pressure 4and the pusher means and lever means are relatively slidiably engaged under the iniiuence of the spring means such that the extension of the Iline of contact between the pusher means and the heel groove extends below the tensile elements, and when the extension of the line of contact between the pusher means and t-he heel groove is raised above the tensile elements in response to an excessive tensile force acting on the heel, release occurs, said lever means including adjustable rack means extending in the Ilongitudinal direction of the ski for bearing on the uppers of the boot to enable the position for use of the lever means to be preset relative to the uppers of the boot.

References Cited UNITED STATES PATENTS 168,980 i0/ 1875 Giffard 2617-65 3,055,673 9/1962 Marker 280-11225 3,190,635 6/ 196-5 Wustenhagen et al. 2617--65 3,249,365 5/1966 Beyl 28011.35

FOREIGN PATENTS 495,510 8/1953 Canada. 1,110,856 10/1955 France. 1,190,118 3/1959 France.

LEO FRIAGLIA, Primary Exwnner.

MILTON L. SMITH, Assistant Examiner. 

